Field
Exemplary embodiments relate to an active noise control apparatus for a vehicle, and more particularly, to an active noise control apparatus for a vehicle, which is capable of expanding the number of microphones regardless of the number of external amplifiers, thereby effectively collecting and removing noise generated in the vehicle.
Discussion of the Background
In general, a vehicle includes a large number of devices installed therein. Recently, devices for a driver's or passenger's convenience have been steadily developed and installed in vehicles. Representative examples of the devices may include an audio system or air conditioning system. Furthermore, more and more vehicles are employing a navigation system installed therein, the navigation system recognizing the location of a vehicle through a satellite or the like and guiding the vehicle to the destination.
Recently, a technology for removing noise generated in a vehicle through an audio system has been developed.
The noise within the vehicle may be generated as a result of sound of an engine or sound of a wind introduced during operation of the vehicle. Furthermore, the noise may be generated while the vehicle travels on an uneven road.
In general, a method for reducing such noise includes a passive noise control method which reduces noise through a sound absorbing material installed in the vehicle, and an active noise control method which reduces a noise signal by outputting a control signal having a phase opposite that of the noise signal.
According to the recent trend, more and more consumers want to purchase a more comfortable and quiet vehicle. Thus, much attention has been paid to the active noise control method, which exhibits a more excellent effect than the passive noise control method, when reducing low-frequency noise, such as engine noise, generated by the vehicle.
An active noise control apparatus which is generally employed in a vehicle includes a microphone, a DSP module, an amplifier, and a speaker. The microphone detects noise, the DSP module includes an adaptive digital filter and a signal controller so as to invert the phase of the detected noise, the amplifier amplifies the phase-inverted noise, and the speaker plays the amplified noise.
Furthermore, the active noise control apparatus generates an artificial sound having the same magnitude as, but the opposite phase to, noise introduced into the vehicle, and superposes the two signals to attenuate or remove the noise.
The related art of the present invention is disclosed in Korean Patent Laid-open Publication No. 10-2008-0091438, published on Oct. 13, 2008, and entitled “Active noise control method and system for a vehicle”.
The number of microphones included in the conventional active noise control apparatus is determined according to the performance of target noise control and a position in the vehicle. In general, two to four microphones are included.
At this time, in order to collect various noise sources in the vehicle, the number of microphones mounted in the vehicle needs to be increased.
However, because the microphones included in the conventional active noise control apparatus are directly connected to an external amplifier, installation of an additional microphone may not be possible. Furthermore, as the number of microphones is increased, the length and weight of a wiring harness for connecting the external amplifier to the microphones are inevitably increased.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept, and, therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.